单选题
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The predictability of our mortality rates is something that has long puzzled social scientists. After all, there is no natural reason why 2,500 people should accidentally shoot them- selves each year or why 7,000 should drown or 55,000 die in their cars. No one establishes a quota for each type of death. It just happens that they follow a consistent pattern year after year.
A few years ago a Canadian psychologist named Gerald Wilde became interested in this phenomenon. He noticed that mortality rates for violent and accidental deaths throughout the Western world have remained oddly static throughout the whole of the century, despite all the technological advances and increases in safety standards that have happened in that time. Wilde developed an intriguing theory called “risk homeostasis”. According to this theory, people instinctively live with a certain level of risk. When something is made safer, people will get around the measure in some way to reassert the original level of danger. If, for instance, they are required to wear seat belts, they will feel safer and thus will drive a little faster and a little more recklessly, thereby statistically canceling out the benefits that the seat belt confers. Other studies have shown that where an intersection is made safer, the accident rate invariably falls there but rises to a compensating level elsewhere along the same stretch of road. It appears, then, that we have an innate need for danger.
In all events, it is becoming clearer and clearer to scientists that the factors influencing our lifespan are far more subtle and complex than had been previously thought. It now appears that if you wish to live a long life, it isn't simply a matter of adhering to certain pre cautions—eating the right foods, not smoking, driving with care. You must also have the right attitude. Scientists at the Duke University Medical Center made a 15-year study of 500 persons personalities and found, somewhat to their surprise, that people with a suspicious or mistrustful nature die prematurely far more often than people with a sunny disposition. Looking on the bright side, it seems, can add years to your life span.

单选题 What social scientists have long felt puzzled about is why______.

单选题 In his research, Gerald Wilde finds that technological advances and increases in safety standards______

单选题 According to the theory of "risk homeostasis ", some traffic accidents result from______

【正确答案】 A

【答案解析】细节理解题问题是“根据体内风险平衡理论，某些交通事故是由于什么原因”， [A]“我们天生的冒险欲望”；[B] “开快车，开鲁莽车”；[C]“无视安全带的好处”；[D]“对超速行驶的本能兴趣”。在第二段后部分，作者先列举交通事故例子，然后在最后一句得出结论：It appears，then，that we have an innate need for danger．符合[A]项意思。

单选题 By saying "... statistically canceling out the benefits that the seat belt confers" ( Para. 2), the author means______

【正确答案】 C

【答案解析】句意理解题本句大体意思是：从数字统计的角度说，开快车开鲁莽车(导致的死亡人数的增加)抵消了系保险带(引起的死亡人数减少)的好处。cancel out解释为“抵消，对消”。所以[C]项“因为其他原因引起的死亡抵消了系保险带的好处”符合题意。[A]和[D]都包含系保险带没有好处，不对，系保险带有benefits，会降低这方面原因导致的死亡事故。[B]“系安全带与不系安全带的死亡人数一样”，无此意。

单选题 Which of the following may contribute to a longer life span?

【正确答案】 C

【答案解析】语义理解题题目问什么有助于长寿，依据最后一段。[A] “对别人信任不要怀疑”，不合文章的意思，倒数第二句是说疑惑心重的人比乐观豁达的人早逝；[B]项不对，文小说“eating the right foods”，并不等于说吃低脂食物；[C]项正确，“an optimistic personality and never losing heart”都是“a sunny disposition”的特征；[D]项后半部分不对。